一个长方体长60cm,如果沿着高的方向把它切成两个小长方体,表面积增加了50平方厘米,原来长方体的体积是多少?

1.1500 cubic centimeter.表面积增加了50,就是增加了两个侧面面积,那么一个侧面面积就是25square centimeter,乘以长60cm,就是1500
2.设长宽高为abc,那么2（ab+ac+bc）=100,就是2ab+2c（a+b）=100,ab=18,2（a+b）=20所以c=3.2 那么体积等于abc=3.2*18= 57.6
3.Look,the boy on the right is my good friend,Wang Bing.The girl on the left is his classmate,Li Fang.Their English teacher is a nice lady.She comes form Bejing.But Mrs Hu still teaches us Engilsh this term.